In this work, the hydrophobization of lignocellulosic jute fibers was achieved via the laccase/TEMPO-mediated grafting of octadecylamine (OA) on their surface, with the aim to improve the interfacial compatibility with nonpolar polylactic acid (PLA) resins in fiber-reinforced composites. The modified jute fibers were analyzed by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS). The characteristic vibrations of methylene groups and the increase in the surface C/O ratio of the jute fibers after the enzymatic treatment indicated that OA molecules were successfully grafted onto the jute fiber surface mediated by the laccase/TEMPO system. It was shown that the grafted jute fibers had increased surface hydrophobicity and reduced polarity with water contact angle of 124.2 °, diiodomethane contact angle of 94.1 ° and surface free energy of 11.44 mJ/m 2 , which were attributed to the presence of the OA nonpolar alkyl chains on their surface. The tensile, bending, and dynamic mechanical properties of the hydrophobized jute/PLA composites were enhanced, which suggested stronger interfacial adhesion between the jute fibers and the PLA matrix. The mechanical stability was investigated by water immersion measurements and it was found that the modified jute/PLA composites were better in this regards than the control jute/PLA composites. Therefore, this enzymatic hydrophobic modification could be used as an effective and eco-friendly method to produce natural lignocellulosic fiber-reinforced composites with excellent performance.
Xinru Wang,Jiangang Wu,Shumei Xia,Keli Yang,Ran Jia,Xin Liu
Potassium chloride is an important inorganic product widely used in agriculture, chemical industry, medicine, dyes and other fields. In China, quite a part of KCl produced via flotation technique, using hydrochloride octadecylamine (ODA-H) as the flotation agent. The residue of ODA-H will influence product quality or cause different problems, which have gained much attention. However, recent studies focus on the purification techniques based on dissolution-recrystallization process, significantly increasing production cost and causing practical challenges. Herein, a simple but efficient method was presented for the in-situ desorption of ODA-H from the surface of KCl in high salt system. Results revealed that the removal efficiency of ODA-H can be significantly influenced by cations, especially Li + , which the removal efficiency can increase to 60 %. Importantly, the desorption was verified by in-situ Raman spectrum, further proving the exceptional removal rate by Li + rather than the non-dissolution effects. DFT simulated results manifested the function of Li + , which illustrated the large lattice deformation and the strong adsorption effects, not only in acidic condition but also in neutral system. This study will open a new route for the removal of contaminant from the surface of soluble solid in concentrated salt solution.
Bin Liu,Bin Liu,Jinkai Li,Jinkai Li,Jinkai Li,Guangbin Duan,Min Ji,Yizhong Lu,Tao Yan,Bingqiang Cao,Zongming Liu,Zongming Liu
Organic-inorganic hybrid perovskite nanocrystals have been widely studied for their excellent photoelectric properties. However, the irregular morphologies of organic-inorganic hybrid perovskite nanocrystals have limited application in the field of lighting and display. From this, the regular morphologies of nanospheres, nanorods, nanoplatelets and MAPbBr3 (MA = CH3NH3+) nanocrystals have been synthesized by regulating the type and proportion of auxiliary ligands. The phase evolution, morphology and fluorescent properties were systematically studied by the various instruments of XRD, TEM, PL/UV-vis spectroscopy and fluorescence decay analysis. With the morphologies changing from nanospheres to nanoplatelets, the emission peaks of MAPbBr3 nanocrystals red-shifted, and the lifetimes have increased gradually. The underlying mechanisms were thoroughly investigated and elucidated. On this basis, the role of acid and amine in the synthesis of MAPbBr3 nanocrystals was systematically studied by regulating the ratio of oleic acid and N-octylamine. The fluorescence kinetics of MAPbBr3 nanocrystals were studied by femtosecond transient absorption spectroscopy, and the charge carrier relaxation mechanism was clarified. Furthermore, the effect of temperature on the fluorescence properties of the nanocrystal was investigated in detail. Organic-inorganic hybrid perovskite nanocrystals with morphologies-controlled and excellent fluorescence properties are expected to be widely used in lighting and display fields.
危险品化学品经营许可证（带存储）